<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .parent{

            display: flex;

            width:550px;
            height:380px;
            background-color: darkblue;
        }
        .item{
            /*设置元素在子元素在主轴方向上的初始大小，，而且优先级高于width
            */
            flex-basis: 200px;
            width:100px;
            height:100px;
            background-color: darkgoldenrod;
        }
        .parent .item:nth-child(3){
    ]
            background-color: #004b00;
            flex-shrink: 0;/*0是我的宽度不能被压缩*/
        }

    </style>
</head>
<body>
<div class="parent">
    <div class="item">1</div>
    <div class="item" style="background-color: saddlebrown">2</div>
    <div class="item">3</div>
    <div class="item">1</div>
    <div class="item" style="background-color: saddlebrown">2</div>
    <div class="item">3</div>
    <div class="item">1</div>
    <div class="item" style="background-color: saddlebrown">2</div>
    <div class="item">3</div>


</div>
</body>
</html>